This invention relates generally to biopsy needles, and more particularly to a biopsy needle with an improved capability for excising tissue specimens and for cauterizing the wound and the tissue in contact with the needle after the tissue specimen has been taken.
Various types of biopsy devices are known. Patents which disclose manual, spring operated biopsy devices include: U.S. Pat. No. 4,917,100 (Nottke) and U.S. Pat. No. 4,733,671 (Mehl). These biopsy devices comprise a cannula which is a hollow, rod-shaped member, and a stylet which is slidably mounted in the cannula. With the stylet positioned so that its end tip is adjacent the end of the cannula, the biopsy needle is inserted into the tissue of a person. The stylet has a notch or recess for holding the tissue specimen near its end, adjacent to the piercing tip. To take the tissue specimen, the stylet is then thrust forward into the area in which the specimen is desired. The cannula which has a sharp edge at its end, is then moved forward toward the end of the stylet, causing the sharp end of the cannula to excise tissue which is then held in the recess of the stylet. The biopsy device, with the specimen enclosed in the recess, is then removed from the body of the patient.
Devices which apply cauterizing heat to the body are shown in U.S. Pat. No. 4,016,881 (Rioux et al.) and U.S. Pat. No. 3,938,527 (Rioux et al.) which discloses a gun-shaped device which inserts electrodes into the body for cauterizing of tubes; and U.S. Pat. No. 4,776,334 (Prionas) which discloses a device for cauterizing tumors.
Other patents including U.S. Pat. No. 1,813,902 (Bovie); U.S. Pat. No. 3,648,001 (Anderson et al.); and U.S. Pat. No. 2,275,167 (Bierman) disclose surgical instruments which use electrical energy for cauterization or for cutting purposes.
My patent, U.S. Pat. No. 5,295,990, discloses a tissue sampling and removal device which comprises a pair of cutting jaws with a heat insulated inner surface defining a chamber for retaining the tissue cut by the jaws. A conductor carries electrical energy which heats the device, thereby cauterizing the tissues surrounding the jaws prior to removal of the excised tissue specimen.
Existing biopsy devices have several major shortcomings. The cutting of the tissue to excise a tissue specimen by moving the sharp end of the cannula forward over and past the recess in the stylet causes bunching of tissue and cutting which is often ragged and not sharp. Furthermore, if the biopsy needle is used to excise tissue specimens from a suspected cancer tumor or cancer infected area of the body, withdrawal of the needle after the specimen has been taken could well leave a trail of displaced cancer cells in the path of the removal of the biopsy needle, thereby proliferating the locations of the cancer.
In view of the foregoing, a biopsy needle with an improved cutting capability and which prevents the spread of cancer cells during the taking of tissue specimens as provided by the instant invention is needed.